Question

question 14 of 25
what effect do keystone species have on an ecosystem?
a. they eliminate prey species.
b. they cause secondary disturbances.
c. they keep populations under control.
d. they reduce biodiversity.

Explanation:

Keystone species play a crucial role in maintaining the balance of an ecosystem. They often act as predators that regulate the population sizes of their prey. By doing so, they prevent any one species from over - populating and out - competing others. For example, sea otters (a keystone species) control sea urchin populations. If sea urchins were not controlled, they would overgraze kelp forests. This regulation helps in maintaining biodiversity (so option D is wrong as they do not reduce biodiversity), they do not eliminate prey species (option A is wrong as elimination would disrupt the food web too much), and they are not known for causing secondary disturbances (option B is wrong). Their main effect is population control.

Answer:

C. They keep populations under control.